The association of certain HLA-tissue types with chronic Chagas' disease noted previously could not be confirmed in a much expanded study. B-cell typing remains to be checked and basic immunogenetic information concerning the Brazilian population has been a useful by-product of the study. The plaquing technique for intracellular phase T. cruzi shows promise as a tool for clonal selection and analysis of isolates of the parasite. Other applications of cell culture for characterization of strains of T. cruzi include temperature tolerance and growth curves. Use of the foot-pad site for inoculation of BALB/c mice and subsequent measurements of the lesion has proved to be a useful model experimental work with strains of cutaneous leishmaniasis.